Mobile storage tank



FIG. 1 is a front elevational view of a mobile storage tank showing my new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a right side elevational view thereof with the tank lids open, a left side elevational view being substantially the same as the right side elevational view shown; and,

FIG. 4 is a top plan view thereof with the tank lids closed, the bottom view being substantially unornamented. 

The ornamental design for a mobile storage tank, as shown and described. 